Huge numbers of fasteners are used in aircraft manufacturing operations. Most or all of these are rivet-like in shape and have a circular head and a cylindrical body. Usually the body has either a threaded or ribbed portion.
It is important to inspect aircraft fasteners prior to use because they may be misshaped or have other flaws. Currently, one method of inspection is to use an optical comparator that is fitted with transparent overlays. This device produces an image of a fastener subject to inspection which shows its actual dimensions, and these dimensions are compared with an overlay showing the fastener's desired dimensions. Typically, each type and size of fastener has a unique set of overlays for gauging fillet radius, head protrusion and head angle. Certain measurements, such as shank and head diameter, are taken with micrometers.
Past methods of fastener inspection have been known to be very time consuming and lacking in adequate precision. The present invention overcomes these drawbacks by providing an automatic inspection device that utilizes machine vision and robotics to accomplish precise inspection automatically. How the invention accomplishes this is set forth below.